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llvm-6502/lib/CodeGen/TargetInstrInfo.cpp
Rafael Espindola 3f0ce4fa18 Fix a lot of confusion around inserting nops on empty functions. 
On MachO, and MachO only, we cannot have a truly empty function since that
breaks the linker logic for atomizing the section.

When we are emitting a frame pointer, the presence of an unreachable will
create a cfi instruction pointing past the last instruction. This is perfectly
fine. The FDE information encodes the pc range it applies to. If some tool
cannot handle this, we should explicitly say which bug we are working around
and only work around it when it is actually relevant (not for ELF for example).

Given the unreachable we could omit the .cfi_def_cfa_register, but then
again, we could also omit the entire function prologue if we wanted to.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217801 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-15 18:32:58 +00:00

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//===-- TargetInstrInfo.cpp - Target Instruction Information --------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the TargetInstrInfo class.
//
//===----------------------------------------------------------------------===//
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/PseudoSourceValue.h"
#include "llvm/CodeGen/ScoreboardHazardRecognizer.h"
#include "llvm/CodeGen/StackMaps.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCInstrItineraries.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include <cctype>
using namespace llvm;
static cl::opt<bool> DisableHazardRecognizer(
"disable-sched-hazard", cl::Hidden, cl::init(false),
cl::desc("Disable hazard detection during preRA scheduling"));
TargetInstrInfo::~TargetInstrInfo() {
}
const TargetRegisterClass*
TargetInstrInfo::getRegClass(const MCInstrDesc &MCID, unsigned OpNum,
const TargetRegisterInfo *TRI,
const MachineFunction &MF) const {
if (OpNum >= MCID.getNumOperands())
return nullptr;
short RegClass = MCID.OpInfo[OpNum].RegClass;
if (MCID.OpInfo[OpNum].isLookupPtrRegClass())
return TRI->getPointerRegClass(MF, RegClass);
// Instructions like INSERT_SUBREG do not have fixed register classes.
if (RegClass < 0)
return nullptr;
// Otherwise just look it up normally.
return TRI->getRegClass(RegClass);
}
/// insertNoop - Insert a noop into the instruction stream at the specified
/// point.
void TargetInstrInfo::insertNoop(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI) const {
llvm_unreachable("Target didn't implement insertNoop!");
}
/// Measure the specified inline asm to determine an approximation of its
/// length.
/// Comments (which run till the next SeparatorString or newline) do not
/// count as an instruction.
/// Any other non-whitespace text is considered an instruction, with
/// multiple instructions separated by SeparatorString or newlines.
/// Variable-length instructions are not handled here; this function
/// may be overloaded in the target code to do that.
unsigned TargetInstrInfo::getInlineAsmLength(const char *Str,
const MCAsmInfo &MAI) const {
// Count the number of instructions in the asm.
bool atInsnStart = true;
unsigned Length = 0;
for (; *Str; ++Str) {
if (*Str == '\n' || strncmp(Str, MAI.getSeparatorString(),
strlen(MAI.getSeparatorString())) == 0)
atInsnStart = true;
if (atInsnStart && !std::isspace(static_cast<unsigned char>(*Str))) {
Length += MAI.getMaxInstLength();
atInsnStart = false;
}
if (atInsnStart && strncmp(Str, MAI.getCommentString(),
strlen(MAI.getCommentString())) == 0)
atInsnStart = false;
}
return Length;
}
/// ReplaceTailWithBranchTo - Delete the instruction OldInst and everything
/// after it, replacing it with an unconditional branch to NewDest.
void
TargetInstrInfo::ReplaceTailWithBranchTo(MachineBasicBlock::iterator Tail,
MachineBasicBlock *NewDest) const {
MachineBasicBlock *MBB = Tail->getParent();
// Remove all the old successors of MBB from the CFG.
while (!MBB->succ_empty())
MBB->removeSuccessor(MBB->succ_begin());
// Remove all the dead instructions from the end of MBB.
MBB->erase(Tail, MBB->end());
// If MBB isn't immediately before MBB, insert a branch to it.
if (++MachineFunction::iterator(MBB) != MachineFunction::iterator(NewDest))
InsertBranch(*MBB, NewDest, nullptr, SmallVector<MachineOperand, 0>(),
Tail->getDebugLoc());
MBB->addSuccessor(NewDest);
}
// commuteInstruction - The default implementation of this method just exchanges
// the two operands returned by findCommutedOpIndices.
MachineInstr *TargetInstrInfo::commuteInstruction(MachineInstr *MI,
bool NewMI) const {
const MCInstrDesc &MCID = MI->getDesc();
bool HasDef = MCID.getNumDefs();
if (HasDef && !MI->getOperand(0).isReg())
// No idea how to commute this instruction. Target should implement its own.
return nullptr;
unsigned Idx1, Idx2;
if (!findCommutedOpIndices(MI, Idx1, Idx2)) {
assert(MI->isCommutable() && "Precondition violation: MI must be commutable.");
return nullptr;
}
assert(MI->getOperand(Idx1).isReg() && MI->getOperand(Idx2).isReg() &&
"This only knows how to commute register operands so far");
unsigned Reg0 = HasDef ? MI->getOperand(0).getReg() : 0;
unsigned Reg1 = MI->getOperand(Idx1).getReg();
unsigned Reg2 = MI->getOperand(Idx2).getReg();
unsigned SubReg0 = HasDef ? MI->getOperand(0).getSubReg() : 0;
unsigned SubReg1 = MI->getOperand(Idx1).getSubReg();
unsigned SubReg2 = MI->getOperand(Idx2).getSubReg();
bool Reg1IsKill = MI->getOperand(Idx1).isKill();
bool Reg2IsKill = MI->getOperand(Idx2).isKill();
// If destination is tied to either of the commuted source register, then
// it must be updated.
if (HasDef && Reg0 == Reg1 &&
MI->getDesc().getOperandConstraint(Idx1, MCOI::TIED_TO) == 0) {
Reg2IsKill = false;
Reg0 = Reg2;
SubReg0 = SubReg2;
} else if (HasDef && Reg0 == Reg2 &&
MI->getDesc().getOperandConstraint(Idx2, MCOI::TIED_TO) == 0) {
Reg1IsKill = false;
Reg0 = Reg1;
SubReg0 = SubReg1;
}
if (NewMI) {
// Create a new instruction.
MachineFunction &MF = *MI->getParent()->getParent();
MI = MF.CloneMachineInstr(MI);
}
if (HasDef) {
MI->getOperand(0).setReg(Reg0);
MI->getOperand(0).setSubReg(SubReg0);
}
MI->getOperand(Idx2).setReg(Reg1);
MI->getOperand(Idx1).setReg(Reg2);
MI->getOperand(Idx2).setSubReg(SubReg1);
MI->getOperand(Idx1).setSubReg(SubReg2);
MI->getOperand(Idx2).setIsKill(Reg1IsKill);
MI->getOperand(Idx1).setIsKill(Reg2IsKill);
return MI;
}
/// findCommutedOpIndices - If specified MI is commutable, return the two
/// operand indices that would swap value. Return true if the instruction
/// is not in a form which this routine understands.
bool TargetInstrInfo::findCommutedOpIndices(MachineInstr *MI,
unsigned &SrcOpIdx1,
unsigned &SrcOpIdx2) const {
assert(!MI->isBundle() &&
"TargetInstrInfo::findCommutedOpIndices() can't handle bundles");
const MCInstrDesc &MCID = MI->getDesc();
if (!MCID.isCommutable())
return false;
// This assumes v0 = op v1, v2 and commuting would swap v1 and v2. If this
// is not true, then the target must implement this.
SrcOpIdx1 = MCID.getNumDefs();
SrcOpIdx2 = SrcOpIdx1 + 1;
if (!MI->getOperand(SrcOpIdx1).isReg() ||
!MI->getOperand(SrcOpIdx2).isReg())
// No idea.
return false;
return true;
}
bool
TargetInstrInfo::isUnpredicatedTerminator(const MachineInstr *MI) const {
if (!MI->isTerminator()) return false;
// Conditional branch is a special case.
if (MI->isBranch() && !MI->isBarrier())
return true;
if (!MI->isPredicable())
return true;
return !isPredicated(MI);
}
bool TargetInstrInfo::PredicateInstruction(MachineInstr *MI,
const SmallVectorImpl<MachineOperand> &Pred) const {
bool MadeChange = false;
assert(!MI->isBundle() &&
"TargetInstrInfo::PredicateInstruction() can't handle bundles");
const MCInstrDesc &MCID = MI->getDesc();
if (!MI->isPredicable())
return false;
for (unsigned j = 0, i = 0, e = MI->getNumOperands(); i != e; ++i) {
if (MCID.OpInfo[i].isPredicate()) {
MachineOperand &MO = MI->getOperand(i);
if (MO.isReg()) {
MO.setReg(Pred[j].getReg());
MadeChange = true;
} else if (MO.isImm()) {
MO.setImm(Pred[j].getImm());
MadeChange = true;
} else if (MO.isMBB()) {
MO.setMBB(Pred[j].getMBB());
MadeChange = true;
}
++j;
}
}
return MadeChange;
}
bool TargetInstrInfo::hasLoadFromStackSlot(const MachineInstr *MI,
const MachineMemOperand *&MMO,
int &FrameIndex) const {
for (MachineInstr::mmo_iterator o = MI->memoperands_begin(),
oe = MI->memoperands_end();
o != oe;
++o) {
if ((*o)->isLoad()) {
if (const FixedStackPseudoSourceValue *Value =
dyn_cast_or_null<FixedStackPseudoSourceValue>(
(*o)->getPseudoValue())) {
FrameIndex = Value->getFrameIndex();
MMO = *o;
return true;
}
}
}
return false;
}
bool TargetInstrInfo::hasStoreToStackSlot(const MachineInstr *MI,
const MachineMemOperand *&MMO,
int &FrameIndex) const {
for (MachineInstr::mmo_iterator o = MI->memoperands_begin(),
oe = MI->memoperands_end();
o != oe;
++o) {
if ((*o)->isStore()) {
if (const FixedStackPseudoSourceValue *Value =
dyn_cast_or_null<FixedStackPseudoSourceValue>(
(*o)->getPseudoValue())) {
FrameIndex = Value->getFrameIndex();
MMO = *o;
return true;
}
}
}
return false;
}
bool TargetInstrInfo::getStackSlotRange(const TargetRegisterClass *RC,
unsigned SubIdx, unsigned &Size,
unsigned &Offset,
const TargetMachine *TM) const {
if (!SubIdx) {
Size = RC->getSize();
Offset = 0;
return true;
}
unsigned BitSize =
TM->getSubtargetImpl()->getRegisterInfo()->getSubRegIdxSize(SubIdx);
// Convert bit size to byte size to be consistent with
// MCRegisterClass::getSize().
if (BitSize % 8)
return false;
int BitOffset =
TM->getSubtargetImpl()->getRegisterInfo()->getSubRegIdxOffset(SubIdx);
if (BitOffset < 0 || BitOffset % 8)
return false;
Size = BitSize /= 8;
Offset = (unsigned)BitOffset / 8;
assert(RC->getSize() >= (Offset + Size) && "bad subregister range");
if (!TM->getSubtargetImpl()->getDataLayout()->isLittleEndian()) {
Offset = RC->getSize() - (Offset + Size);
}
return true;
}
void TargetInstrInfo::reMaterialize(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I,
unsigned DestReg,
unsigned SubIdx,
const MachineInstr *Orig,
const TargetRegisterInfo &TRI) const {
MachineInstr *MI = MBB.getParent()->CloneMachineInstr(Orig);
MI->substituteRegister(MI->getOperand(0).getReg(), DestReg, SubIdx, TRI);
MBB.insert(I, MI);
}
bool
TargetInstrInfo::produceSameValue(const MachineInstr *MI0,
const MachineInstr *MI1,
const MachineRegisterInfo *MRI) const {
return MI0->isIdenticalTo(MI1, MachineInstr::IgnoreVRegDefs);
}
MachineInstr *TargetInstrInfo::duplicate(MachineInstr *Orig,
MachineFunction &MF) const {
assert(!Orig->isNotDuplicable() &&
"Instruction cannot be duplicated");
return MF.CloneMachineInstr(Orig);
}
// If the COPY instruction in MI can be folded to a stack operation, return
// the register class to use.
static const TargetRegisterClass *canFoldCopy(const MachineInstr *MI,
unsigned FoldIdx) {
assert(MI->isCopy() && "MI must be a COPY instruction");
if (MI->getNumOperands() != 2)
return nullptr;
assert(FoldIdx<2 && "FoldIdx refers no nonexistent operand");
const MachineOperand &FoldOp = MI->getOperand(FoldIdx);
const MachineOperand &LiveOp = MI->getOperand(1-FoldIdx);
if (FoldOp.getSubReg() || LiveOp.getSubReg())
return nullptr;
unsigned FoldReg = FoldOp.getReg();
unsigned LiveReg = LiveOp.getReg();
assert(TargetRegisterInfo::isVirtualRegister(FoldReg) &&
"Cannot fold physregs");
const MachineRegisterInfo &MRI = MI->getParent()->getParent()->getRegInfo();
const TargetRegisterClass *RC = MRI.getRegClass(FoldReg);
if (TargetRegisterInfo::isPhysicalRegister(LiveOp.getReg()))
return RC->contains(LiveOp.getReg()) ? RC : nullptr;
if (RC->hasSubClassEq(MRI.getRegClass(LiveReg)))
return RC;
// FIXME: Allow folding when register classes are memory compatible.
return nullptr;
}
void TargetInstrInfo::getNoopForMachoTarget(MCInst &NopInst) const {
llvm_unreachable("Not a MachO target");
}
bool TargetInstrInfo::
canFoldMemoryOperand(const MachineInstr *MI,
const SmallVectorImpl<unsigned> &Ops) const {
return MI->isCopy() && Ops.size() == 1 && canFoldCopy(MI, Ops[0]);
}
static MachineInstr* foldPatchpoint(MachineFunction &MF,
MachineInstr *MI,
const SmallVectorImpl<unsigned> &Ops,
int FrameIndex,
const TargetInstrInfo &TII) {
unsigned StartIdx = 0;
switch (MI->getOpcode()) {
case TargetOpcode::STACKMAP:
StartIdx = 2; // Skip ID, nShadowBytes.
break;
case TargetOpcode::PATCHPOINT: {
// For PatchPoint, the call args are not foldable.
PatchPointOpers opers(MI);
StartIdx = opers.getVarIdx();
break;
}
default:
llvm_unreachable("unexpected stackmap opcode");
}
// Return false if any operands requested for folding are not foldable (not
// part of the stackmap's live values).
for (SmallVectorImpl<unsigned>::const_iterator I = Ops.begin(), E = Ops.end();
I != E; ++I) {
if (*I < StartIdx)
return nullptr;
}
MachineInstr *NewMI =
MF.CreateMachineInstr(TII.get(MI->getOpcode()), MI->getDebugLoc(), true);
MachineInstrBuilder MIB(MF, NewMI);
// No need to fold return, the meta data, and function arguments
for (unsigned i = 0; i < StartIdx; ++i)
MIB.addOperand(MI->getOperand(i));
for (unsigned i = StartIdx; i < MI->getNumOperands(); ++i) {
MachineOperand &MO = MI->getOperand(i);
if (std::find(Ops.begin(), Ops.end(), i) != Ops.end()) {
unsigned SpillSize;
unsigned SpillOffset;
// Compute the spill slot size and offset.
const TargetRegisterClass *RC =
MF.getRegInfo().getRegClass(MO.getReg());
bool Valid = TII.getStackSlotRange(RC, MO.getSubReg(), SpillSize,
SpillOffset, &MF.getTarget());
if (!Valid)
report_fatal_error("cannot spill patchpoint subregister operand");
MIB.addImm(StackMaps::IndirectMemRefOp);
MIB.addImm(SpillSize);
MIB.addFrameIndex(FrameIndex);
MIB.addImm(SpillOffset);
}
else
MIB.addOperand(MO);
}
return NewMI;
}
/// foldMemoryOperand - Attempt to fold a load or store of the specified stack
/// slot into the specified machine instruction for the specified operand(s).
/// If this is possible, a new instruction is returned with the specified
/// operand folded, otherwise NULL is returned. The client is responsible for
/// removing the old instruction and adding the new one in the instruction
/// stream.
MachineInstr*
TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI,
const SmallVectorImpl<unsigned> &Ops,
int FI) const {
unsigned Flags = 0;
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
if (MI->getOperand(Ops[i]).isDef())
Flags |= MachineMemOperand::MOStore;
else
Flags |= MachineMemOperand::MOLoad;
MachineBasicBlock *MBB = MI->getParent();
assert(MBB && "foldMemoryOperand needs an inserted instruction");
MachineFunction &MF = *MBB->getParent();
MachineInstr *NewMI = nullptr;
if (MI->getOpcode() == TargetOpcode::STACKMAP ||
MI->getOpcode() == TargetOpcode::PATCHPOINT) {
// Fold stackmap/patchpoint.
NewMI = foldPatchpoint(MF, MI, Ops, FI, *this);
} else {
// Ask the target to do the actual folding.
NewMI =foldMemoryOperandImpl(MF, MI, Ops, FI);
}
if (NewMI) {
NewMI->setMemRefs(MI->memoperands_begin(), MI->memoperands_end());
// Add a memory operand, foldMemoryOperandImpl doesn't do that.
assert((!(Flags & MachineMemOperand::MOStore) ||
NewMI->mayStore()) &&
"Folded a def to a non-store!");
assert((!(Flags & MachineMemOperand::MOLoad) ||
NewMI->mayLoad()) &&
"Folded a use to a non-load!");
const MachineFrameInfo &MFI = *MF.getFrameInfo();
assert(MFI.getObjectOffset(FI) != -1);
MachineMemOperand *MMO =
MF.getMachineMemOperand(MachinePointerInfo::getFixedStack(FI),
Flags, MFI.getObjectSize(FI),
MFI.getObjectAlignment(FI));
NewMI->addMemOperand(MF, MMO);
// FIXME: change foldMemoryOperandImpl semantics to also insert NewMI.
return MBB->insert(MI, NewMI);
}
// Straight COPY may fold as load/store.
if (!MI->isCopy() || Ops.size() != 1)
return nullptr;
const TargetRegisterClass *RC = canFoldCopy(MI, Ops[0]);
if (!RC)
return nullptr;
const MachineOperand &MO = MI->getOperand(1-Ops[0]);
MachineBasicBlock::iterator Pos = MI;
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
if (Flags == MachineMemOperand::MOStore)
storeRegToStackSlot(*MBB, Pos, MO.getReg(), MO.isKill(), FI, RC, TRI);
else
loadRegFromStackSlot(*MBB, Pos, MO.getReg(), FI, RC, TRI);
return --Pos;
}
/// foldMemoryOperand - Same as the previous version except it allows folding
/// of any load and store from / to any address, not just from a specific
/// stack slot.
MachineInstr*
TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI,
const SmallVectorImpl<unsigned> &Ops,
MachineInstr* LoadMI) const {
assert(LoadMI->canFoldAsLoad() && "LoadMI isn't foldable!");
#ifndef NDEBUG
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
assert(MI->getOperand(Ops[i]).isUse() && "Folding load into def!");
#endif
MachineBasicBlock &MBB = *MI->getParent();
MachineFunction &MF = *MBB.getParent();
// Ask the target to do the actual folding.
MachineInstr *NewMI = nullptr;
int FrameIndex = 0;
if ((MI->getOpcode() == TargetOpcode::STACKMAP ||
MI->getOpcode() == TargetOpcode::PATCHPOINT) &&
isLoadFromStackSlot(LoadMI, FrameIndex)) {
// Fold stackmap/patchpoint.
NewMI = foldPatchpoint(MF, MI, Ops, FrameIndex, *this);
} else {
// Ask the target to do the actual folding.
NewMI = foldMemoryOperandImpl(MF, MI, Ops, LoadMI);
}
if (!NewMI) return nullptr;
NewMI = MBB.insert(MI, NewMI);
// Copy the memoperands from the load to the folded instruction.
if (MI->memoperands_empty()) {
NewMI->setMemRefs(LoadMI->memoperands_begin(),
LoadMI->memoperands_end());
}
else {
// Handle the rare case of folding multiple loads.
NewMI->setMemRefs(MI->memoperands_begin(),
MI->memoperands_end());
for (MachineInstr::mmo_iterator I = LoadMI->memoperands_begin(),
E = LoadMI->memoperands_end(); I != E; ++I) {
NewMI->addMemOperand(MF, *I);
}
}
return NewMI;
}
bool TargetInstrInfo::
isReallyTriviallyReMaterializableGeneric(const MachineInstr *MI,
AliasAnalysis *AA) const {
const MachineFunction &MF = *MI->getParent()->getParent();
const MachineRegisterInfo &MRI = MF.getRegInfo();
// Remat clients assume operand 0 is the defined register.
if (!MI->getNumOperands() || !MI->getOperand(0).isReg())
return false;
unsigned DefReg = MI->getOperand(0).getReg();
// A sub-register definition can only be rematerialized if the instruction
// doesn't read the other parts of the register. Otherwise it is really a
// read-modify-write operation on the full virtual register which cannot be
// moved safely.
if (TargetRegisterInfo::isVirtualRegister(DefReg) &&
MI->getOperand(0).getSubReg() && MI->readsVirtualRegister(DefReg))
return false;
// A load from a fixed stack slot can be rematerialized. This may be
// redundant with subsequent checks, but it's target-independent,
// simple, and a common case.
int FrameIdx = 0;
if (isLoadFromStackSlot(MI, FrameIdx) &&
MF.getFrameInfo()->isImmutableObjectIndex(FrameIdx))
return true;
// Avoid instructions obviously unsafe for remat.
if (MI->isNotDuplicable() || MI->mayStore() ||
MI->hasUnmodeledSideEffects())
return false;
// Don't remat inline asm. We have no idea how expensive it is
// even if it's side effect free.
if (MI->isInlineAsm())
return false;
// Avoid instructions which load from potentially varying memory.
if (MI->mayLoad() && !MI->isInvariantLoad(AA))
return false;
// If any of the registers accessed are non-constant, conservatively assume
// the instruction is not rematerializable.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI->getOperand(i);
if (!MO.isReg()) continue;
unsigned Reg = MO.getReg();
if (Reg == 0)
continue;
// Check for a well-behaved physical register.
if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
if (MO.isUse()) {
// If the physreg has no defs anywhere, it's just an ambient register
// and we can freely move its uses. Alternatively, if it's allocatable,
// it could get allocated to something with a def during allocation.
if (!MRI.isConstantPhysReg(Reg, MF))
return false;
} else {
// A physreg def. We can't remat it.
return false;
}
continue;
}
// Only allow one virtual-register def. There may be multiple defs of the
// same virtual register, though.
if (MO.isDef() && Reg != DefReg)
return false;
// Don't allow any virtual-register uses. Rematting an instruction with
// virtual register uses would length the live ranges of the uses, which
// is not necessarily a good idea, certainly not "trivial".
if (MO.isUse())
return false;
}
// Everything checked out.
return true;
}
/// isSchedulingBoundary - Test if the given instruction should be
/// considered a scheduling boundary. This primarily includes labels
/// and terminators.
bool TargetInstrInfo::isSchedulingBoundary(const MachineInstr *MI,
const MachineBasicBlock *MBB,
const MachineFunction &MF) const {
// Terminators and labels can't be scheduled around.
if (MI->isTerminator() || MI->isPosition())
return true;
// Don't attempt to schedule around any instruction that defines
// a stack-oriented pointer, as it's unlikely to be profitable. This
// saves compile time, because it doesn't require every single
// stack slot reference to depend on the instruction that does the
// modification.
const TargetLowering &TLI = *MF.getSubtarget().getTargetLowering();
const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
if (MI->modifiesRegister(TLI.getStackPointerRegisterToSaveRestore(), TRI))
return true;
return false;
}
// Provide a global flag for disabling the PreRA hazard recognizer that targets
// may choose to honor.
bool TargetInstrInfo::usePreRAHazardRecognizer() const {
return !DisableHazardRecognizer;
}
// Default implementation of CreateTargetRAHazardRecognizer.
ScheduleHazardRecognizer *TargetInstrInfo::
CreateTargetHazardRecognizer(const TargetSubtargetInfo *STI,
const ScheduleDAG *DAG) const {
// Dummy hazard recognizer allows all instructions to issue.
return new ScheduleHazardRecognizer();
}
// Default implementation of CreateTargetMIHazardRecognizer.
ScheduleHazardRecognizer *TargetInstrInfo::
CreateTargetMIHazardRecognizer(const InstrItineraryData *II,
const ScheduleDAG *DAG) const {
return (ScheduleHazardRecognizer *)
new ScoreboardHazardRecognizer(II, DAG, "misched");
}
// Default implementation of CreateTargetPostRAHazardRecognizer.
ScheduleHazardRecognizer *TargetInstrInfo::
CreateTargetPostRAHazardRecognizer(const InstrItineraryData *II,
const ScheduleDAG *DAG) const {
return (ScheduleHazardRecognizer *)
new ScoreboardHazardRecognizer(II, DAG, "post-RA-sched");
}
//===----------------------------------------------------------------------===//
// SelectionDAG latency interface.
//===----------------------------------------------------------------------===//
int
TargetInstrInfo::getOperandLatency(const InstrItineraryData *ItinData,
SDNode *DefNode, unsigned DefIdx,
SDNode *UseNode, unsigned UseIdx) const {
if (!ItinData || ItinData->isEmpty())
return -1;
if (!DefNode->isMachineOpcode())
return -1;
unsigned DefClass = get(DefNode->getMachineOpcode()).getSchedClass();
if (!UseNode->isMachineOpcode())
return ItinData->getOperandCycle(DefClass, DefIdx);
unsigned UseClass = get(UseNode->getMachineOpcode()).getSchedClass();
return ItinData->getOperandLatency(DefClass, DefIdx, UseClass, UseIdx);
}
int TargetInstrInfo::getInstrLatency(const InstrItineraryData *ItinData,
SDNode *N) const {
if (!ItinData || ItinData->isEmpty())
return 1;
if (!N->isMachineOpcode())
return 1;
return ItinData->getStageLatency(get(N->getMachineOpcode()).getSchedClass());
}
//===----------------------------------------------------------------------===//
// MachineInstr latency interface.
//===----------------------------------------------------------------------===//
unsigned
TargetInstrInfo::getNumMicroOps(const InstrItineraryData *ItinData,
const MachineInstr *MI) const {
if (!ItinData || ItinData->isEmpty())
return 1;
unsigned Class = MI->getDesc().getSchedClass();
int UOps = ItinData->Itineraries[Class].NumMicroOps;
if (UOps >= 0)
return UOps;
// The # of u-ops is dynamically determined. The specific target should
// override this function to return the right number.
return 1;
}
/// Return the default expected latency for a def based on it's opcode.
unsigned TargetInstrInfo::defaultDefLatency(const MCSchedModel &SchedModel,
const MachineInstr *DefMI) const {
if (DefMI->isTransient())
return 0;
if (DefMI->mayLoad())
return SchedModel.LoadLatency;
if (isHighLatencyDef(DefMI->getOpcode()))
return SchedModel.HighLatency;
return 1;
}
unsigned TargetInstrInfo::getPredicationCost(const MachineInstr *) const {
return 0;
}
unsigned TargetInstrInfo::
getInstrLatency(const InstrItineraryData *ItinData,
const MachineInstr *MI,
unsigned *PredCost) const {
// Default to one cycle for no itinerary. However, an "empty" itinerary may
// still have a MinLatency property, which getStageLatency checks.
if (!ItinData)
return MI->mayLoad() ? 2 : 1;
return ItinData->getStageLatency(MI->getDesc().getSchedClass());
}
bool TargetInstrInfo::hasLowDefLatency(const InstrItineraryData *ItinData,
const MachineInstr *DefMI,
unsigned DefIdx) const {
if (!ItinData || ItinData->isEmpty())
return false;
unsigned DefClass = DefMI->getDesc().getSchedClass();
int DefCycle = ItinData->getOperandCycle(DefClass, DefIdx);
return (DefCycle != -1 && DefCycle <= 1);
}
/// Both DefMI and UseMI must be valid. By default, call directly to the
/// itinerary. This may be overriden by the target.
int TargetInstrInfo::
getOperandLatency(const InstrItineraryData *ItinData,
const MachineInstr *DefMI, unsigned DefIdx,
const MachineInstr *UseMI, unsigned UseIdx) const {
unsigned DefClass = DefMI->getDesc().getSchedClass();
unsigned UseClass = UseMI->getDesc().getSchedClass();
return ItinData->getOperandLatency(DefClass, DefIdx, UseClass, UseIdx);
}
/// If we can determine the operand latency from the def only, without itinerary
/// lookup, do so. Otherwise return -1.
int TargetInstrInfo::computeDefOperandLatency(
const InstrItineraryData *ItinData,
const MachineInstr *DefMI) const {
// Let the target hook getInstrLatency handle missing itineraries.
if (!ItinData)
return getInstrLatency(ItinData, DefMI);
if(ItinData->isEmpty())
return defaultDefLatency(ItinData->SchedModel, DefMI);
// ...operand lookup required
return -1;
}
/// computeOperandLatency - Compute and return the latency of the given data
/// dependent def and use when the operand indices are already known. UseMI may
/// be NULL for an unknown use.
///
/// FindMin may be set to get the minimum vs. expected latency. Minimum
/// latency is used for scheduling groups, while expected latency is for
/// instruction cost and critical path.
///
/// Depending on the subtarget's itinerary properties, this may or may not need
/// to call getOperandLatency(). For most subtargets, we don't need DefIdx or
/// UseIdx to compute min latency.
unsigned TargetInstrInfo::
computeOperandLatency(const InstrItineraryData *ItinData,
const MachineInstr *DefMI, unsigned DefIdx,
const MachineInstr *UseMI, unsigned UseIdx) const {
int DefLatency = computeDefOperandLatency(ItinData, DefMI);
if (DefLatency >= 0)
return DefLatency;
assert(ItinData && !ItinData->isEmpty() && "computeDefOperandLatency fail");
int OperLatency = 0;
if (UseMI)
OperLatency = getOperandLatency(ItinData, DefMI, DefIdx, UseMI, UseIdx);
else {
unsigned DefClass = DefMI->getDesc().getSchedClass();
OperLatency = ItinData->getOperandCycle(DefClass, DefIdx);
}
if (OperLatency >= 0)
return OperLatency;
// No operand latency was found.
unsigned InstrLatency = getInstrLatency(ItinData, DefMI);
// Expected latency is the max of the stage latency and itinerary props.
InstrLatency = std::max(InstrLatency,
defaultDefLatency(ItinData->SchedModel, DefMI));
return InstrLatency;
}
bool TargetInstrInfo::getRegSequenceInputs(
const MachineInstr &MI, unsigned DefIdx,
SmallVectorImpl<RegSubRegPairAndIdx> &InputRegs) const {
assert((MI.isRegSequence() ||
MI.isRegSequenceLike()) && "Instruction do not have the proper type");
if (!MI.isRegSequence())
return getRegSequenceLikeInputs(MI, DefIdx, InputRegs);
// We are looking at:
// Def = REG_SEQUENCE v0, sub0, v1, sub1, ...
assert(DefIdx == 0 && "REG_SEQUENCE only has one def");
for (unsigned OpIdx = 1, EndOpIdx = MI.getNumOperands(); OpIdx != EndOpIdx;
OpIdx += 2) {
const MachineOperand &MOReg = MI.getOperand(OpIdx);
const MachineOperand &MOSubIdx = MI.getOperand(OpIdx + 1);
assert(MOSubIdx.isImm() &&
"One of the subindex of the reg_sequence is not an immediate");
// Record Reg:SubReg, SubIdx.
InputRegs.push_back(RegSubRegPairAndIdx(MOReg.getReg(), MOReg.getSubReg(),
(unsigned)MOSubIdx.getImm()));
}
return true;
}
bool TargetInstrInfo::getExtractSubregInputs(
const MachineInstr &MI, unsigned DefIdx,
RegSubRegPairAndIdx &InputReg) const {
assert((MI.isExtractSubreg() ||
MI.isExtractSubregLike()) && "Instruction do not have the proper type");
if (!MI.isExtractSubreg())
return getExtractSubregLikeInputs(MI, DefIdx, InputReg);
// We are looking at:
// Def = EXTRACT_SUBREG v0.sub1, sub0.
assert(DefIdx == 0 && "EXTRACT_SUBREG only has one def");
const MachineOperand &MOReg = MI.getOperand(1);
const MachineOperand &MOSubIdx = MI.getOperand(2);
assert(MOSubIdx.isImm() &&
"The subindex of the extract_subreg is not an immediate");
InputReg.Reg = MOReg.getReg();
InputReg.SubReg = MOReg.getSubReg();
InputReg.SubIdx = (unsigned)MOSubIdx.getImm();
return true;
}
bool TargetInstrInfo::getInsertSubregInputs(
const MachineInstr &MI, unsigned DefIdx,
RegSubRegPair &BaseReg, RegSubRegPairAndIdx &InsertedReg) const {
assert((MI.isInsertSubreg() ||
MI.isInsertSubregLike()) && "Instruction do not have the proper type");
if (!MI.isInsertSubreg())
return getInsertSubregLikeInputs(MI, DefIdx, BaseReg, InsertedReg);
// We are looking at:
// Def = INSERT_SEQUENCE v0, v1, sub0.
assert(DefIdx == 0 && "INSERT_SUBREG only has one def");
const MachineOperand &MOBaseReg = MI.getOperand(1);
const MachineOperand &MOInsertedReg = MI.getOperand(2);
const MachineOperand &MOSubIdx = MI.getOperand(3);
assert(MOSubIdx.isImm() &&
"One of the subindex of the reg_sequence is not an immediate");
BaseReg.Reg = MOBaseReg.getReg();
BaseReg.SubReg = MOBaseReg.getSubReg();
InsertedReg.Reg = MOInsertedReg.getReg();
InsertedReg.SubReg = MOInsertedReg.getSubReg();
InsertedReg.SubIdx = (unsigned)MOSubIdx.getImm();
return true;
}
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